The present invention relates to an airbag device (i.e., an airbag module) in which an airbag is inflated to protect a vehicle occupant in the event of a vehicle emergency, such as a collision. More particularly, the present invention relates to an airbag device in which the ratio of the weight of the airbag device to the weight of the steering wheel body is set in order to provide an airbag with reduced weight to keep the vehicle weight down.
An airbag for protecting a vehicle occupant is usually stored in a folded state in a recess disposed in the middle section of a steering wheel of a vehicle or within an instrument panel of a vehicle. In the event of a vehicle emergency, such as a collision, the airbag is deployed and inflated in the vehicle interior by gas produced by an inflator. The inflated airbag receives and retains an occupant.
Conventionally, a fabric for use in an airbag of an airbag device is normally a woven fabric made of synthetic filament yarns having fineness from 500 denier to 630 denier and coated with an elastomer or the like. The conventional base fabric is quite thick because the woven fabric itself is thick and is additionally coated with resin. The folded airbag therefore has a large volume and is heavy. As a result, with conventional airbag devices, the weight of a driver side airbag device and steering wheel may be heavy such that the steering wheel becomes difficult to turn. In such cases, the weight of the vehicle in which the airbag device is mounted is also heavy. Conversely, if the weight of the airbag device and steering wheel is too light, the steering wheel experiences vibration.